Thanks to all of you for your input.

This particular toilet is in the hall bathroom and is uased all day long by
four family members. Thus the constant flow of cold water.
I think after considering all of your suggestions I will go and have a look
at the warm water idea. My husband is good at everything, so it shouldn't be
a big problem for him to connect a small valve with some warmish water
blended into it.

Again, many thanks to all for taking the time and thought to help me with
this problem!

Kate